As previously described [35,36], all [GFAP-tTA;TRE-SMOA1] mice develop large medulloblastoma tumors that can extend along the entire rostral-caudal length of the cerebellum, account for more than a quarter of the total cerebellar volume, express NeuN, indicative of neuronal origin, and show marked proliferative activity (positive for Ki67) (Figure 1b). The gene discussed is MKI67; the disease is medulloblastoma.